(a) Field of the Invention
The present invention relates to a process for manufacturing dried pulses which are almost instantaneously restored to the soft edible condition of boiled raw pulses. More particularly, the invention pertains to a process as described above for the production of dried pulses which can be restored in a very short period of time to their boiled soft edible condition simply by pouring hot water onto the processed dried pulses.
The word "pulses" herein used will hereinafter be substituted by the word "beans" which will signify collectively various kinds of pulses, throughout the specification and the claims.
The beans which are suitable for use in the present invention are those beans which are rich in starch and poor in both protein and fat content.
(b) Description of the Prior Art
The methods for producing processed dried beans which quickly restore the soft edible condition of boiled raw beans include the following known methods: (1) a method comprising first softening raw beans by boiling the beans together with a softening promoter such as polyphosphate to soften also their seed coat, and thereafter immersing the resulting softened beans in a solution such as a saccharine solution, followed by drying the resulting solution-treated beans in heated air; and (2) a method of producing processed dried beans by simultaneously freezing and drying the boiled softened raw beans in vacuo.
However, the processed dried beans produced in accordance with the above-mentioned known method (1) are not easily and quickly restored to their soft boiled edible condition by merely pouring hot water thereonto, because these beans have poor permeability of hot water into the interior of the beans. Whereas, those processed dried beans produced in accordance with the method (2) mentioned above are fairly good in their restorability to boiled edible condition, this restorability still is not satisfactory. Besides, they lack their original flavor and natural good feel to the tongue since the textures and tissues of the cells of the beans themselves have been indiscriminately destroyed during the freezing-drying treatment.
As stated, the restorability of those processed dried beans obtained according to the known processes (1) and (2) mentioned above is invariably not satisfactory. The present inventors have earlier proposed, in U.S. Pat. No. 4,214,007, a method for producing processed dried beans which almost instantaneously restores the condition of boiled soft raw beans simply by pouring hot water onto the processed dried beans, by first boiling raw beans in hot water, and then subjecting the boiled beans to an enzymatic treatment by contacting said boiled beans with an aqueous solution containing an enzyme selected from a group consisting of cellulase and a mixture of cellulase and pectinase at a pH of acidic to neutral, and thereafter drying said beans. By this previously proposed method, the insufficient restorability to the soft edible condition of dried beans by the already known methods has been improved to some extent. According to this previously proposed method, however, there is the disadvantage that the pectic intercellular substances which have been somewhat destroyed during the enzymatic treatment are destroyed further in a secondary boiling which is customarily carried out. Thus, there is the tendency for the occurrence of deformation of the original configuration of the beans. In addition, this prior method carries out drying by means of heated air. Accordingly, only the surface portion of beans dries first, and gradually the drying progresses into the interior portion of the beans. As such, during the initial period of the drying step, there occurs a great difference in the degree of drying between the surface portion and the core portion of the beans. As a result, the surface of the beans tends to curve or bulge outwardly, causing cracks and fractures to develop, thus spoiling the external appearance of the product dried beans. Thus, the dried beans according to said previously proposed method are good in quick restorability to boiled edible condition when poured with hot water, but their external appearance still has much to be improved.